Province of Saskatchewan

Transcription

1 Flyash Projects in Saskatchewan Collaborative Seminar Series on Responsible Use of Supplementary Cementing Materials (SCMs) in Performance Based Specifications" January 30, Province of Saskatchewan Estevan 2 1

2 3 SaskPower Coal Fueled Generating Stations Shand Power Station Poplar River Power Station Boundary Dam Power Station 4 2

3 SaskPower Coal Fueled Generating Stations Boundary Dam Power Station Began generating power in the 1950s Generating capability: 882 MW off 6 units Plant consumes 4.92 million tonnes of lignite coal annually Produces 365,000 tonnes of Class CI flyash annually Ash for sale is collected off 3 units SaskPower International exclusive marketer Supplies 80-85% of flyash used in Saskatchewan 5 Mill Test Results Boundary Dam 6 3

4 SaskPower Coal Fueled Generating Stations Shand Power Station Began generating power in the 1992 Generating capability: 306 MW Plant consumes 1.83 million tonnes of lignite coal annually Produces 131,400 tonnes of Class CH flyash annually SaskPower International exclusive marketer 7 Mill Test Results Shand 8 4

5 Boundary vs. Shand 9 Rules for Using Flyash In Concrete Ensure flyash meets CSA Standard A specifications Most important to the Redi mix industry are fineness, LOI and consistency Regular testing according to CSA standards Maintain good quality control practices Monitor field air contents, strengths, etc. Monitor field results 10 5

6 Projects that have incorporated an unconventional us of Flyash ICF housing in Regina and Saskatoon SSWHR Hospital in Swift Current Centennial Wind Facility SW Saskatchewan 11 ICF Housing in Saskatoon and Regina Local Redi-Mix supplier Problem increase Flow of plastic concrete to facilitate better consolidation while maintaining competitive cost of product Solution increase percentage of Flyash Used in mix design 12 6

7 13 ICF Housing in Saskatoon and Regina Solution consisted of changing the basic wall mix presently in use to a 50 % Fly Ash and 50 % Type GU cement mix design, And a Reduction of maximum coarse aggregate size. Test results are consistently >30Mpa on a 25Mpa mix design Approximately 20 houses each year are constructed this way 14 7

8 15 SSWHR Hospital in Swift Current Problem: undesirable soil conditions Construction adjacent to existing hospital Accelerated Construction schedule Traditional solution would be to use a driven piling system Solution Proposed and accepted by Southwest Saskatchewan Health authority: Continuous Flight Auger ( CFA ) Augercast Piles 16 8

9 Continuous Flight Auger ( CFA ) Augercast Piles INTRODUCTION Auger Cast Piles are installed by rotating a continuously flighted hollow shaft auger into the soil to a specified depth Without extraction of any soil. High strength cement grout is pumped under pressure through the hollow shaft of the auger as the auger is slowly withdrawn. The resulting grout column hardens and forms an auger cast pile. Reinforcing, when required, can be installed while the cement grout is still fluid. Augercast piles are available in a range of 400mm 1000mm diameters with depths to 17m. Depths to 45m possible with special rigging. 17 Continuous Flight Auger ( CFA ) Augercast Piles Auger Cast Piles can be used: As friction piles - the superstructure load is transferred to the soil through friction between the pile surface and the soil; As an end-bearing pile - the superstructure load is transferred through the pile tip into a hard stratum of soil or rock; As an anchor pile - hydrostatic or other uplift forces are resisted though a full length tendon embedded in the grout column; As a vertical component of a continuous curtain wall in temporary or permanent shoring systems and below grade walls; and As a temporary or permanent diagonal tie-back in auger cast curtain walls, beam and lagging walls, and sheet pile walls. 18 9

10 Continuous Flight Auger ( CFA ) Augercast Piles 19 Continuous Flight Auger ( CFA ) Augercast Piles ADVANTAGES Less noise - Auger cast piles are a drilled and pumped pile, not a driven pile. This eliminates the hammer impact noise created by driving piles. No objectionable vibration - The elimination of a pile-driving hammer allows the installation of auger cast piles adjacent to existing structures without the danger of settlement or damage to existing footings, walls, other structural components, or nearby equipment. No casing required - During the installation of an auger cast pile, the earth filled auger maintains the shape of the pile hole during the drilling phase. The pressures produced by the grout pump during the withdrawal and grouting phase exceed the lateral pressures exerted by the soil, and while the gout is still fluid, the lateral pressures per foot of depth of the grout exceed those pressures per foot of depth of the soil. Soil at each pile hole can be inspected - The grout that is pumped into the pile displaces the existing soil for the entire length of the pile. This displacing action allows the soil along the length of the extracted auger to be available for visual inspection and testing

11 Continuous Flight Auger ( CFA ) Augercast Piles Concrete Spec: Compressive Strength- 32 MPa Air 4-7% Slump-200+/- 20mm W/C Ratio Mix Design: per cubic meter: 14mm Rock-675kg Fine aggregate- 530 kg Type HS Cement- 310 kg FlyAsh- 310 kg Water-200 litre High Range water reducer-1.8 litre Water Reducer ml Air entraining agent- 240 ml 21 Continuous Flight Auger ( CFA ) Augercast Piles Swift Current Hospital 2005 Tests 1 & 7 mpa Day 7 Day 14 Day 28 Day 56 Day Age 22 11

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14 Centennial Wind Power Facility Project: 83 turbines, capable of putting out a total of 150 megawatts enough to power 64,000 homes. The final structure, from ground to the top of the rotor when a blade is pointing straight up, is 107 metres tall: roughly the height of a 30-story building. 27 Centennial Wind Power Facility 2 TYPES OF FOUNDATIONS 1) Spread footings Total = 57 See attached mix design Base dimensions = approx. 14m(46') x 14m(46') Depth = approx. 1.9m(6.3') to 2.3m(7.5') Concrete Volumes: -Mud slab = 25 yd3 -Main foundation = 190 yd3 -Pedestal = 10 yd3 -TOTAL = 225 yd3 2) P&H Foundations (Patrick & Henderson) Total = 26 See attached mix design Depth = 9.75m (32') CMP=Corrugated Metal Pipe Outter CMP Diameter = 4.0m(13') Inner CMP Diameter = 3.2m(10.6') Void on outside of outter CMP ranges from 6" to 3' Slurry is poured in thirds up the foundation on outside of outter CMP(waiting 6-8 hrs between pours to prevent collapse of CMP). Amount of slurry ranges between 80 to 300 yd3 Concrete, anchor bolts, and rebar placed between inner and outter CMP (2.5' thick). Concrete volume: approx. 65 yd3 Inside of inner CMP backfilled with loose uncompacted native backfill

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16 Centennial Wind Power Facility CONSTRUCTION METHODOLOGY -Excavate hole with track hoe. -Place mud slab on unfrozen ground. -Provide heat and hoarding to area to prevent freezing of mud slab and undisturbed soil below it. -The undisturbed soil below the mud slab will not be allowed to freeze. -Heating and hoarding removed and replaced to allow for placement of rebar. -During placement of concrete, heating and hoarding will ensure rebar temperature meets CSA A23.1 requirements. -Concrete will be cured for 3 days at a minimum of 10C OR the time necessary to achieve 40% of 28 day compressive strength. Field cured concrete cylinders will be taken and tested to verify curing period. -Once curing period has elapsed heaters will be removed and tarps will be left on to prevent thermal shock of the concrete. -Foundations will be backfilled with unfrozen native material and compacted to specified standard proctor densities Foundations were installed between January and July, Centennial Wind Power Facility 32 16

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22 Centennial Wind Power Facility 43 Questions? 44 22